Does closing usually happen on time? Who attends?

We agreed with the sellers to close on April 14th. We put that into our offer because we are currently renting and do not want a double payment. We also have a lock in rate that expires that day. Will the lender try to push it back to avoid the lock in? Is there anyway to protect myself against that move? Also, the sellers have to travel from Denver to Lansing Mi for this. Shouldn't the lender take this into consideration? STRESSFUL!!!!